Rural labor transfer and agricultural mechanization are interacted and interrelated, and jointly propel the change of grain production in China. To better promote China’s grain production and to improve national grain security, this paper constructed an analytical framework of grain production change under the integrated impacts of rural labor transfer and agricultural mechanization by the Kaya identical equation and the Logarithmic Mean Weigh Division Index Method, which examines the integrated impacts based on four driving forces, including the scale effect, the quantity effect, the equipment effect, and the efficiency effect, representing the scale of grain planted area, the input of rural labor force per acer, the per capita possession of agricultural machinery, and the grain yield, respectively. In addition, this paper also analyzed the influences of the four driving effects on grain production in China and its 31 provinces (not including Hongkong, Macao and Taiwan) from 2003 to 2018. Results show that: 1) whether from the temporal or the spatial perspective, the influence of the quantity effect on grain production was obviously negative, while the influences of the scale effect and the equipment effect on grain production were significantly positive, which were quite typical in major grain producing areas; 2) From 2003 to 2018, the influence of the efficiency effect on grain production changed from negative to positive at the national level. However, the influence was remarkably negative in 24 provinces at the provincial level. Therefore, to keep a sustainable and stable grain production increase in China’s major grain producing areas, it is necessary to continuously enhance supports in policy & finance, to stabilize rural labor force, to further strengthen grain security responsibility in main grain-consuming areas, and to promote the development of agricultural mechanization of grain production in different regions across the country.